Method of preparing catalytic materials



" synthesis of ammonia.

Patented May 29?, 1928..

j tenses GEORGES CLAUDE, 0F PARIS, FRANCE, ASSIGNOR, BY MESNEASSIGNMENTS, "1'0 LAZOTE INC., A CORPORATION OF DELAWARE.

m n'rxon or rnnrenme CATALYTIC mernnmns.

R0 Drawing. Application filed October 21, 1920, Serial No. 418,447, andin France October 28, new.

This invention relates to improvements in methods of producing catalyticmaterials, adapted particularly for use in the synthetic production ofammonia.

When a bar of iron or of ordinary steel is melted in a suitablecontainer by heating a portion thereof to a White heat, with an to be avery poor catalyzer, yielding generally with pressures of the order ofone thousand atmospheres a mixture containing only from about one tenthto-one or two per cent of ammonia. The poor catalytic properties of thismaterial are due apparent- 1y to its large content of iron and .loweroxide of iron. At any rate Iv have found that the material'obtained bymelting and burning iron as above described can be made into a moreefficient catalyst if the melted mass is subjected to further oxidationby a jet of 0 gen.

Accor ing to the present invention, the above mentioned material, madeby fusing hi hly heated ironwith an oxygen jet, is su jected, while itis still in a molten or fused state, to the action of a{ jet of oxygenwhich brings about a further considerable elevation of temperature,evidently due to the combination of further amounts of, oxygen with theoxide.

oxygen content of the oxide results in a This increase is very greatincrease in the catalytic activity of the oxide when used in thecatalytic Thus, by this method a catalyst is obtained which yields underthe above-named conditions of pressure, flow and temperature, acomposition reachin to of ammonia. This material, owever, althougli' itshows a verygreat increase in catalytic activity, has a relatively shortlife, even with very pure reacting gases.

I have found that the catalytic activity of this oxide can be stillfurther increased and the efiectivelife of the oxide, as a catalyst, canbe rolonged b therewith a .suitab e amount 0 magnesia.

combining following Pecific description 'illus oxygen. When a suflicientquantity of the molten oxidized mass containin some molten iron iscollected in the cruclble, say some kilograms, for example, and whilethe mass is still molten, a jet of oxygen, sufiiciently intense to causean energetic stirring is directed upon the molten mass. An enormouselevation in temperature is produced in consequence of the combustion ofthe metallic iron and the further oxidation of the mass. This increasein temperature is such that a considerable proportion of the magnesia ofthecrucible is dissolved inthe liquid. It is therefore necessary toemploy an unusually refractory material such as magnesia for thecontainer of the molten oxide'during this operation. The resultingoxidized product thus produced is cast on a sheet of iron, and, aftersuitable comminutlon, constitutes an excellent catalyzer for themanufacture of ammonia.

When the catalyzer. thus employed is used in the synthetic production ofammonia, for example, at a pressure of 1000 atmospheres and atemperature of about 600 (1., and with a considerable volume through thecatalyzer inJthe order of 100 liters per hour per cubic centimeter. ofcatalyzer, the ammonia content of the-result ing gases may be as high asto corresponding to a combination of to ofthe reacting gases. I

The catalyzer produced as above described, while' it enables a highpercentage conversion of the reacting gases to be obtained, neverthelesshasa relatively short eflective life, decreasinglrnaterially in itscatalytic power in a period of, for example, 10 to 15 hours. p

I have found that a .catalyzer which combines the advantageouspropertiesof high conversion with long life can beroduced by adding other bodiesto the oxi ized oxide, part cularly by the addition of lime.

of gases passing stirring,

from 5 to 10% of lime is added in successive increments to the cruciblewhile it is being filled with the molten oxide of iron, and a jet ofoxygen of large cross-section is projected on the fused material withsufficient velocity to bring about a vigorous the lime is rapidlydissolved, sometimes with considerable swelling. If the metal containsobjectionable impurities, the further oxidation should be carriedfurther and should be continued until the surface of the liquid bathbegins to con eal. If the oxide is free from objectionab e impurities,the operation can be arrested as soon as the mixture becomessufliciently homogeneous and when all the pasty iron at the bottom ofthe crucible has been converted into oxide and further oxidized. Even inthis case, however, the maximum. oxidation, that is to say, whencontinued until the surface of the bath congeals, can be effectedgenerally without objectionable result, and is almost always desirablefrom the standpoint of the life of the catalyzer and the proportion ofammonia roduced.

When t e oxidation has been completed,

the material is then cast into sheets and broken up into particles ofthe desired fineness for use in the catalytic chamber. It forms acatalyzer which combines the advantages of very great initial activitywith long life. The catalyzer may thus be used for a lon period of time,for example, up to severa hundreds of hours, before the proportion ofammonia roduced has decreased to half the origina proportion.

The catalytic activity of the catalyst can be further improved by addinalkali metal oxids in small proportion to t e lime.

The catalzyer produced as above described is of particular value for usein the synthetic production of ammonia under hyper-pressures of theorder of 1000 atmospheres, although the catalyzer is available for usefor other purposes. The catalyzer is thus of particular advantage foruse in the synthetic production of ammonia according to the process ofmy prior United States PatentNo. 1,332,460, and, when so used, gives ahigh percentage conversion of the reacting gases. This high percentageconversion can be obtained with the oxide even without the addition oflime; but this high percenta e conversion can be combined with long eective life if the lime is combined with the material in the mannerabove described. r In the carrying out of the synthetic, ammouniaprocess, the improved catalyzer, produced as above described, may beplaced in asuitable catalytic chamber, for example,

in an a paratus such as is illustrated and 2. The method of preparing anim roved I catalyst, which comprises melting an burning iron until it issubstantiall oxidized and thereafter directing a blast 0 oxygen upon themolten mass to raise the temperature thereof.

3. The method of preparing an improved catalyst, which comprisesdirecting a blast of oxygen upon a molten mass of incompletely oxidizediron to raise the temperature thereof.

4. The method of preparing an improved catalyst, which comprises meltingand burning iron and thereafter subjecting the molten mass to a blast ofoxygen until the surface of the molten mass begins to congeal.

5. The method of preparing an improved catalyst, which comprisesdirecting a blast of oxygen upon a molten mass of incompletely oxidizediron until the surface of the molten mass begins to congeal.

6. The method of preparing an improved catalyst, which comprises meltin,and burning iron until it is substantial y oxidized and thereaftersubjecting, the molten mass obtained to agitation produced by a blast ofoxygen directed on the mass with accompanying rise in temperature'of themass.

7 The method of preparing an improved catalyst, which comprisessubjecting a molten mass of incompletely oxidized iron to agitationproduced by a blast of oxygen directed on the mass with accompanyingrise in temperature of the mass.

8. The method of preparing an improved catalyst, which comprises meltingand burn iron and maintaining it while molten in an atmosphere of oxygenuntil the mass begins to congeal.

In testimony whereof I aflix my signature.

GEORGES CLAUDE.

